25 Surprising Facts About Fish and Life Underwater

The underwater world is packed with creatures that are stranger, tougher, and more adaptable than most people realize. From fish that climb walls and live beneath Antarctic ice to species with shocking abilities and surprising behaviors, these facts reveal just how extraordinary life below the surface can be.

Tuna’s Self Cooking Power

1. The warm-blooded Atlantic Bluefin Tuna is so powerful that when fighting fisherman it can cook its own flesh with sudden bursts of muscle activity.

2. In April 2015, scientists observed several armored catfishes climbing the walls of a cave in Ecuador. It was also the first time scientists discovered that catfishes had evolved to live in underground water bodies.

3. More species of fish are found in the Amazon River than are recorded in the entire Atlantic Ocean.

4. Female fishes have sometimes been observed faking orgasms to dupe males into believing they have copulated. They then swim off to find a better partner.

5. Some horse owners put goldfish in the water troughs to keep them free of insects like mosquitoes and algae.

6. In Ancient Rome, doctors used a primitive form of electrotherapy to successfully treat neurological conditions such as epilepsy and migraines by placing electric torpedo fish on the patient’s head to administer the charges.

7. The crocodile icefish does not use blood to carry oxygen; instead it absorbs oxygen directly from the water through its skin.

8. Goldfish have teeth situated at the back of their throat.

9. Round goldfish bowls are banned in Monza, Italy because, in the words of the authorities, ‘a fish kept in a bowl has a distorted view of reality’.

10. Sardine is not a single species name but a general term applied to various small, oily fishes within the herring family Clupeidae.

Eyes Migrate, Sides Change Color

11. Halibut are born with an eye on each side of the head and swim similarly to salmon. After about six months, one eye moves to the other side, giving them a flounder-like appearance. At the same time, the side with the fixed eye darkens to match the upper side, while the opposite side remains white.

12. The practice of keeping goldfish in bowls arose from a misunderstanding of Chinese display vessels. Those vessels were small, temporary containers used to show goldfish to guests; the fish were otherwise kept in ponds. Fishbowls are so harmful to goldfish that some cities, including Rome, prohibit them on the basis of animal cruelty.

13. A fish called the needlefish can leap from the water and impale people while moving at speeds up to 37 mph; multiple human fatalities have been recorded.

14. The likelihood of being attacked by a candiru (a penis invading fish) is said to be about the same as the likelihood of being struck by lightning while simultaneously being eaten by a shark.

15. Researchers have found fish and some other aquatic animals living beneath Antarctic ice, under 740 meters of ice in a 10-meter-deep section of water. Scientists remain unsure how these organisms manage to sustain themselves.

16. The eulachon contains enough oil to be ignited, and the Nisga’a people used it as a source of light.

17. In 2014, Nat Geo Wild aired ‘Fish Bowl,’ a four-hour clip of a goldfish swimming in a bowl, during both the Super Bowl and the Puppy Bowl.

18. Indonesia discovered that a dead manta ray is worth $500, whereas manta ray tourism generated $1,000,000 over the lifetime of a single ray; Indonesia is now the largest manta sanctuary.

19. Goldfish were originally silver; during the Song Dynasty in ancient China, the imperial family bred them until they became yellow because the imperial family liked yellow.

20. Electric eels are apex predators because animals that could eat them avoid doing so to avoid being shocked.